Atrial fibrillation is one of the most common arrhythmias in the world and is recognized as one of the most serious medical epidemics. Atrial fibrillation is a leading cause of stroke, thromboembolism, mortality, and debilitation. Common debilitating symptoms of atrial fibrillation include but are not limited to palpitations, dyspnea, dizziness, chest pain, weakness, and long term debility associated with stroke and congestive heart failure. There is a large economic burden to society associated with atrial fibrillation including: medical care costs resulting from medical therapy, symptom relief, hospitalizations, and invasive procedure and device therapy; lost time from the workforce; and long term care costs associated with morbidity of stroke, heart failure, and debilitation.
The current drug-related therapies for atrial fibrillation require relatively high doses of drugs systemically to effect the substrate tissue in the atrium in order to have any positive effect. However, these drugs have serious side effects, and are largely inadequate. One therapy for atrial fibrillation comprises ventricular rate control drugs. However, common side effects of this therapy include bradycardia, weakness, low energy levels, and other side effects. Moreover, this treatment may require pacemaker implantation which is invasive and costly. Another adjunctive therapy for atrial fibrillation comprises blood thinners. However, blood thinners have significant side effects and may lead to minor and catastrophic bleeding complications, may require frequent blood tests, and may have a narrow and difficult to achieve therapeutic window to achieve therapeutic blood levels. Still another therapy for atrial fibrillation comprises antiarrhtyhmic drugs. However, antiarrhtyhmic drugs have a limited effectiveness in maintaining normal heart rhythm, and have a wide range of toxic systemic side effects. Moreover, antiarrhtyhmic drugs may induce pro-arrhythmia, and have negative drug interactions with other medications.
The current procedural therapies for atrial fibrillation are also largely inadequate. One procedure for atrial fibrillation comprises electrical cardioversion. This procedure requires sedation or general anesthesia. Moreover, atrial fibrillation commonly reoccurs after electrical cardioversion. Another procedure for atrial fibrillation comprises invasive catheter ablation such as: radiofrequency ablation; cryothermy; ultrasound ablation; laser ablation; or electrical ablation. Catheter ablation is intended to ablate arrhythmogenic cells in or around the left atrium. The majority of cases are known to originate from the endocardium or myocardium within or around the pulmonary veins. Creating circumferential ablation lesions around pulmonary veins is intended to cause electrical isolation of the abnormal cells within the pulmonary veins, rending these trigger zones unable to propagate abnormal electrical impulses into the left atrium, making them incapable of causing atrial fibrillation. Pulmonary vein ablation for atrial fibrillation remains a promising therapy, but has proven to be each of the following: limited in efficacy; have risks and complications associated with an invasive procedure; require specialized skill and training leading to higher costs, and a lower number of patients that can be treated due to the lack of operators with this specialized training; require a long procedure time to effectively map, through electrophysiology mapping, specific trigger zones around the pulmonary vein ostia prior to delivering the catheter based injury; and often require repeat procedures for a successful outcome. Moreover, current catheter ablation techniques are limited in their success in part due to the inability to deliver the ablative injury to all substrate tissue that causes atrial fibrillation. This limitation may leave potential gaps in the target area of ablation that is not treated. This is often caused due to limitations in controlling the catheter tip and the inability to provide multiple burns at the end of the catheter in the same spot due to the risk of perforation. Frequently, patients are required to return for multiple repeat procedures in attempts to ablate missed areas. Current catheter-based therapies are hampered by their inability to consistently, effectively, and predictably create circumferential, continuous, or curvilinear ablation lines to eradicate origins of irregular electrical activity, and to isolate the target tissue from further propagating abnormal electrical impulses. Serious complications related to current ablation therapies include: left atrial perforation leading to hemopericardium and cardiac tamponade; pulmonary vein stenosis; left atrial-espohageal fistula; thromboembolic events, such as stroke and myocardial infarction, resulting directly from injury created by current equipment and techniques, and other complications.
An apparatus and process is needed to effectively treat atrial fibrillation, or other types of non-atrial fibrillation issues involving mammalian tissue, while avoiding one or more of the side-effects associated with the current treatments.